1. Field of the Invention
The invention is generally related to motion conversion apparatus. More particularly, the invention is concerned with tool slide actuation in a generating tool head wherein at least one tool point is capable of simultaneous axial and transverse motion relative to a work surface on which tapered threadforms are to be generated. 2.
Description of the Prior Art
While the invention is useful in a variety of mechanical systems, it is described herein for use with a taper thread generating head coupled to the spindle assembly of a pipe threading machine tool system. Such threading systems are known and are set up to perform the general overall task of generating an external tapered thread at the end of pipe sections appropriately chucked in substantial axial alignment with the generating head. As the housing of the tool head is advanced axially of the pipe section, or other workpiece, thread cutting elements are moved axially as well as radially, or transversely, of the toolhead axis to thereby generate a thread form which gradually tapers outwardly such that the maximum depth of cut occurs at the end of the pipe or workpiece first engaged by such cutting elements. At the end of the cutting stroke, or threading pass, the cutting elements must be further moved transversely of the tool head housing axis to provide clearance between the pipe or workpiece and the cutting elements as the tool head is backed away to a restart position for the next pipe or workpiece to be threaded.
The motion conversion apparatus employed in these prior art thread generating heads typically comprises complicated camming elements, often requiring a separate camming mechanism for converting axial to transverse motion for each of a plurality of cutting tool holders associated with the generating head. Providing separate mechanisms for each holder may lead to component matching problems preventing uniformity of movement of each cutting element with respect to the workpiece. Additionally, the linear or arcuate camways and associated cam followers of the prior art motion conversion apparatus are often unsuited for the higher speeds and feeds which may be typically employed with carbide cutting elements.
The most pertinent prior art known to applicant is set forth in the disclosures of the following United States Letters Patent:
U.S. Pat. No. 2,054,028, Benninghoff, Sept. 8, 1936 PA1 U.S. Pat. No. 3,812,548, Theuerkaue, May 28, 1974 PA1 U.S. Pat. No. 3,129,445, Jennings, April 21, 1964 PA1 U.S. Pat. No. 3,254,548, Gersch, June 7, 1966 PA1 U.S. Pat. No. 3,286,556, Reynolds et al., Nov. 22, 1966 PA1 U.S. Pat. No. 3,443,458, Ohrnberger et al., May 13, 1969 PA1 U.S. Pat. No. 4,004,332, Wawrzniak, Jan. 25, 1977 PA1 U.S. Pat. No. 4,040,315, Bellingham, Aug. 9, 1977 PA1 U.S. Pat. No. 4,066,380, Beck et al., Jan. 3, 1978
It will therefore be seen that there is a need in the pertinent art field for a motion conversion mechanism capable of smoothly converting mechanical motion of cutting elements of generating heads capable of use with a variety of machine tool spindle assemblies at relatively higher feeds and speeds than in the past, and capable of being relatively easily manufactured and assembled. Further, a review of the prior art demonstrates a need for such apparatus that is capable of being at least manually adjustable as to its produced results without complicated disassembly of many of the components of the apparatus being required.